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Genomics Introduction

The geneticists have worked to identify map of genes in organisms of interest. The efforts were gradually centered on a few organisms, such as Drosophila, maize, mice, bacteria, and yeast. Mapping of genes involved in following two steps. The first step consisted of identification of spontaneous mutations, or mutants induced by chemical or physical agents. Once a set of mutation was available, they were used for linkage analysis and preparation of linkage maps. In some organisms, such as Drosophila, physical map of genes’ locations on chromosomes were also created. This approach was efficient and widely used in genetics. The drawback of this approach is that at least one mutation for each gene in the genome is required. But obtaining mutation is a difficult. In addition, the mutation must produce phenotypic effect. But mutations often have a lethal effect making it difficult or impossible to map the mutated gene.

In 1980, geneticists began to use recombinant DNA technology for genetic analysis. In this approach, a collection of clones called a genomic library is established. These clones are pieced together into overlapping sets and assembled into genetics and physical maps for the entire genome. In the final step, the clones are sequenced and all the genes in the genome are identified by from this sequence.

The term genomics was coined by Thomas H. Roderick in 1987. At that time, the genomics term means mapping and sequencing to analyze the structure and organization of genomes. But today, genomics includes sequencing of genomes, determination of complete set of proteins encoded by an organism, and the functioning of genes and metabolic pathways in an organism. Thus genomics not only deals with the determination of genetic information present in an organism, but also with understanding the mechanism by which this information is used by the organism. The term genome was introduced by I-I. Winkler in 1920. Genome means the complete set of chromosomal and extra-chromosomal genes present in an organism.

The information generated in genomics is very wide. Interpretation and management of this information requires the use of powerful computers and specific software. Bioinformatics is an emerging field concerned with the development and application of computer hardware and software to the acquisition, storage, analysis, and visualization of biological information. Database for the storage and analysis of genome information are now essential tools for geneticists. The proteomics is the study of gene products encoded by a genome, including a list of the genes that are expressed, their time of expression, and the type and extend of any post- translational modification of gene product, the function of the encoded protein and its location in various cellular compartments.

The discipline of genomics is often divided into the two domains, (i) structural genomics and (ii) functional genomics. Structural genomics deals with the determination of the complete sequence of genomes or the complete set of proteins produced by an organism. Often the Structural genomics also includes determination of the three-dimensional structures of concerned proteins. The functional genomics deals with studies the functioning of genes and metabolic pathways, i.e., the gene expression patterns in organism.

Genomics History

The idea of genome sequencing was discussed in the specific community during 1984 onwards. In 1986, a proposal was prepared for sequencing of human genome. The human Genome Project officially began on 1 Oct. 1990. The first genome to be sequenced was that of Haemophilus influenza in1995. The E. coli genome was soon to be completely sequenced in1997. Yeast (Saccharomyces cerevisae) and worm (Caenorhabditis elegans) was first eukaryotic genomes to be sequences in 1999. One year later, in 2000, genomes of Drosophila melanogaster and Arabidopsis thaliana were sequenced. On 26 June, 2001, the rough draft of human genome was announced. This draft was prepared separately by the public funded.